In the semiconductor industry, it is known that growing a III-N material, such as GaN, on a silicon substrate is difficult due in large part to the large crystal lattice mismatch (−16.9%) between silicon and GaN. Thus, some type of template is generally formed on the silicon substrate and the III-N material is grown on the template. It is also known that during any of the growth process there must ideally be no exposed silicon surface due to detrimental reaction between the III-N material (e.g. Ga) and silicon. In the prior art a common process for protecting the silicon surface of a substrate (i.e. a wafer or portion thereof) is to grow an amorphous thermal oxide layer on the surface, for example by thermal oxidation of the surface. One problem is that the amorphous silicon oxide also prevents the direct growth of a crystalline III-N layer.
It would be highly advantageous, therefore, to remedy the foregoing and other deficiencies inherent in the prior art.
Accordingly, it is an object of the present invention to provide new and improved methods for the formation of a crystalline rare earth template on a silicon substrate.
It is another object of the present invention to provide new and improved methods for the conversion of an amorphous thermal oxide layer on the surface of a silicon substrate into a crystalline rare earth template for the subsequent growth of III-N areas.